As explained in the article "What is
Canon?" only information directly taken from the episodes or movies can
be canonical. However, in fandom, and even in official publications, a number of
notions are commonly regarded as canonical facts although there is little to no
support for them. Reasons for such false canon are that fans are constantly
attempting to rationalize problems or to fill gaps in biographies or
specifications. In some other cases, misconceptions and over-interpretations of
canon facts have been perpetuated, sometimes unconsciously in official reference
books.

Note Many
more examples may be added if we take into account a number of ship class
names, registries or other secondary evidence that were likely made up behind
the scenes, by Gene Roddenberry (Yorktown was renamed to Enterprise
NCC-1701-A), by Greg Jein (Constitution registries) or by the Okudas (registry
of the USS Antares) without ever appearing on screen. But seeing that much
of this information is required in order to be able to call designs by their
names, such little facts are accepted as apocryphal canon here at EAS. And
eventually the NCC-501 of the USS Antares even made the transition from
apocryphal to full canon when it appeared in TOS-R: "Charlie X".

History
and Politics

"Australia
was the last country to join the United Earth Government in 2150."

This statement is downright wrong. In TNG:
"Attached" Dr. Crusher just picked Australia as a hypothetical
example of a country not becoming a member until 2150. Beverly actually said, "What if one
nation, let's say Australia, had not joined...?"

"Spock was
the first Vulcan in Starfleet."

This is a widespread statement in official publications
as well as in fandom, but it was never stated in any TOS episode or movie.
Actually, the idea may have originated as behind-the-scenes information,
considering that Spock was supposed to be an exceptional person in any
conceivable respect. Still, it is dubious in the light of the Intrepid (TOS:
"The Immunity Syndrome"), a Starfleet ship with an all-Vulcan crew
which we wouldn't expect less than two decades after Spock was the first
Vulcan to join Starfleet Academy. Clearly Spock's presence on the Enterprise
NCC-1701 is no obstacle for T'Pol to become the true first Vulcan Starfleet
officer a hundred years earlier (albeit of Earth Starfleet).

"Women were not allowed to become starship captains in the 2260s."

"Your world of starship captains doesn't admit women",
Janice Lester's complaint from TOS: "Turnabout Intruder", seems to
be corroborated by the lack of female captains at that time. But it is just an
awkward interpretation that there used to be a regulation of Starfleet
generally not to admit female captains. First off, Lester was a nutball so her
statement is suspect from the start. Secondly, she could have meant that life
as a starship Captain is not conducive to having long-term relationships with
women, which would seem to be supported for the most part in Trek with a few
notable exceptions. Thirdly, the statement just does not fit with the stated
beliefs and goals of Star Trek and Roddenberry and is quite honestly offensive
if that is the way it was meant, so it is best forgotten. With the female
captain of NX-02 (ENT: "Home") the myth has been refuted anyway.(Patrick Carroll)

"Starfleet has a department called the 'Starfleet Marines'."

Starfleet Marines are exceedingly popular, and no online
RPG could possibly exist without them. There is some scarce evidence for a
distinct department that may encompass ground troops: the rank of colonel
(namely Colonel West) in the extended version of "Star Trek: The
Undiscovered Country" and personnel with previously unseen uniforms in
DS9: "Nor the Battle to the Strong" and "The Siege of
AR-558". However, there is neither a mention of a distinct part of
Starfleet's military organization, much less particularly of
"Marines". The word "Marines" has been used behind the
scenes though (by uniform designer Nilo Rodis, as mentioned in
The Making of the Final Frontier). The special forces on Enterprise
NX-01 are called "MACOs", not "Marines" (where MACO is not
supposed to stand for "MArine COrps").

"Alpha Centauri is an alien world and
a founding member of the Federation."

Until ENT: "Twilight" when it was ultimately
confirmed that Alpha Centauri is a human colony, the star system was mentioned
only once or twice altogether and never as an alien world or a founding member
of the UFP. Well, Alpha Centauri is said to be a founding member in Picard's scrapbook in "Generations",
but this was far from being readable in the movie.

"Zefram Cochrane was a native of Alpha Centauri."

It is odd how some fans uphold this stance based
on a single line from TOS: "Metamorphosis", although Cochrane is
identified as human in the TOS episode and "Star
Trek: First Contact" makes it clear beyond the slightest doubt that
Cochrane (whose first and last name are of human origin, by the way) is a
human being who has never seen any aliens. He may have moved to Alpha Centauri
at a later date, but as of 2063 he has never left the planet. The myth
probably came into existence in the (non-canon) book Spaceflight Chronology,
where an Earth ship arrives at Alpha
Centauri and made first contact with Zefram Cochrane.

"Earth fought and eventually won a series of wars against the Kzinti in
the 21st century."

The Kzinti only appeared in TAS: "The Slaver
Weapon", an episode written by Larry Niven as a cross-over with his Known
Space series. First of all, this certainly doesn't imply that anything from
the Known Space novels with their totally incompatible timeline is
canon in the Star Trek Universe. Secondly, we have to keep in mind that the
popularity of the Kzinti in fan fiction
has no bearing on the question. Thirdly, the
canon status of TAS is debatable anyway. But if we presuppose that TAS is
or can be canon, what can we make of Sulu's statement about the Kzinti Wars that ended "200
years ago"? Well, the wars would have taken place in a time when
Earth was in no shape to fight an interstellar war, much less win it.
Moreover, the wars ought to have been mentioned on many occasions. There is no
way that the Kzinti Wars can be canon, unless we ignore or re-interpret facts
and statements from several live-action episodes that depict a wholly
different 21st century. There are ways for the Kzinti to exist in canon Trek,
but not with the historical background of "The Slaver Weapon".

"The Romulan War,
during which Earth received support from Andor and Tellar, led to the founding of the Federation."

Clearly the two events took place at about the same
time, as was ultimately confirmed in the final season of Star Trek Enterprise,
so the statement would absolutely make sense. But there is no evidence
that the foundation of the Federation is a direct consequence of the war. We
do not know either whether Earth really received support from two other
founding members (the fourth being the Vulcans who were neutral as we can
easily imagine).

"The Vulcan home system is Epsilon Eridani."

The canon central star of Vulcan is 40 Eridani A, not
Epsilon Eridani. 40 Eridani was once proposed
by astrophysicists to Gene Roddenberry, who liked the idea. With the
distance from Earth to Vulcan mentioned in ENT: "Home" being 16
light years, the distance of 40 Eridani A, we now have the missing canon
confirmation. Alas, when a Jupiter-like gas planet was found in orbit of the
star Epsilon Eridani, this planet was nicknamed in the media as
"Vulcan", based on the wrong supposition that Epsilon Eridani was
the central star.

"Epsilon Indi is the Andorian homeworld, 61 Cygni is the Tellarite
homeworld."

Neither can be in any way confirmed. Actually, both star
systems Epsilon Indi and 61 Cygni are just mentioned in the Star Trek
Technical Manual by Franz Joseph, even with depictions of their seals and
flags. But anything relating them to Andor or Tellar, respectively, is missing
in this context, even if we saw canonical relevance in the book.

"The Romulans call themselves
Rihannsu."

This idea is fanon of a quite consistent kind. The name
"Rihannsu" was never spoken out on screen and is therefore
non-canon. But it appeared in the novels of the Rihannsu
Book series (the first being My Enemy, My Ally) and in Spock's World,
all by Diane Duane, which explains why it has become quite popular.

"The Cardassians were unknown to the Federation prior to the 24th century.
The mention of Cardassians in Enterprise and in 'Star Trek (2009)' is an error."

There is nothing in canon Trek to support this notion,
other than a lack of Cardassians in TOS and the TOS movies. The obvious
real-world reason is that the Cardassians were created for TNG: "The
Wounded".

"Archer's threat at the end of ENT: 'Acquisition' had a lasting effect. The
Ferengi didn't show up for more than 200 years."

A few words don't determine the course of the history of
a whole civilization for 200 years. Archer's line, just like the conspicuous
avoidance of the name "Ferengi", is nothing but an attempt to
justify retroactively that the episode with its problematic
continuity was made in the first place.

"The first contact between humanity and the Klingon Empire was in 2218."

No one can really tell where this information comes
from. The Star Trek Encyclopedia states that the year was 2218, based
on a line by McCoy in TOS: "Day of the Dove". The doctor allegedly
mentioned the duration of human-Klingon hostilities which was interpreted
hereafter as the time since the first contact. But in reality he didn't say
anything implying a time. The only coarse date ever given for the first
encounter of humans and Klingons was in the TNG episode "First
Contact" where it was said to have been "centuries ago".
In this light it is absolutely realistic that this took place in 2151, the
year of ENT: "Broken Bow".

"In the 2260s many Klingons were surgically altered to deal with humans or
to infiltrate the Federation."

Although it has been ultimately
refuted in the Klingon arc of ENT: "Affliction" and
"Divergence", this old myth is still occasionally resurrected on
message boards. But even fans who disregard Star Trek Enterprise should
recognize how moronic it would be to alter Klingon faces to look human but
still give them unmistakably Klingon garments, weapons or ships. Not to
mention the disgrace that would lie in such a ploy...

"There are two distinct Klingon languages, Klingonese/Klingonaase and
tlhIngan Hol."

In canon Star Trek, a rudimentary set of phrases devised
by James Doohan for "Star Trek: The Motion Picture" was developed
into a fully-fledged Klingon language by Marc Okrand for TNG. Both were always
treated as being identical. The language was simply
called "Klingon (language)" on screen, "Klingonese" on
rare occasions and initially "Klingonee" (at least that's what it
sounds like) in TOS: "The Trouble with Tribbles"
before anyone actually spoke any Klingon words. "Klingonese" should
not be confused with "Klingonaase", which is a fragmentary non-canon
language devised by John M. Ford for his novel The Final Reflection,
later also in FASA games and in Star Fleet Battles. The name "tlhIngan
Hol" for the canon language supposedly never made it to the screen
either.

"V'ger was the origin of the Borg."

It's a nice theory considering that Decker merged
with the mechanical entity V'ger in "Star Trek: The Motion Picture".
However, it was refuted as early as in TNG: "Q Who" when Guinan said
about them: "They're made up of organic and artificial life, which has been developing for thousands of centuries."
In a couple of Voyager episodes, for
instance VOY: "The Omega Directive" and "Dark Frontier",
it is implied likewise that the Borg have been around for thousands of years.

"The Tholian emblem is a red hollow triangle."

The triangular Tholian emblem is depicted in the Star
Trek Star Charts by Geoffrey Mandel. It originates in the short-lived
science fiction series "Space: Above and Beyond", where it
represented the Chigs. The explanation how the emblem found its way into the
Trek reference book is simple: Geoffrey Mandel worked as a graphics artist for
that series. This is also why we can safely assume that the emblem never
showed up in a canon Trek production. The Tholian emblem is a one-time
exception in the Star Trek Star Charts. Several other obscure emblems
can be found in the book, but could all be identified as canon.

"The
hadrosaurs survived the mass extinction 65 million years ago on a lost continent. Eventually they grew into an advanced society and left for the stars, losing track of their homeworld along the way."

Chakotay suggested this in VOY: "Distant
Origin" without providing any proof. It is nothing more than a theory,
and not a particularly good one. The first problem is that it would be highly unlikely for hadrosaurs to survive the extinction. Secondly,
it's hard to believe such an advanced species would limit itself to a single "lost continent" instead of occupying the entire Earth. And that this society would leave no satellites or solar system colonies or ruins anywhere to acknowledge their existence. Third, why would they leave their homeworld so far behind and choose a completely nomadic lifestyle, so much so that they forgot where they came from? Fourth, a large continent could not just sink out of existence, some trace of it would be found. Fifth, how would
their civilization affect the growth of mammalian species after the dinosaurs died out?
-- An alternative and more likely idea would be that an alien species such as the Preservers came along and, recognizing the
hadrosaurs' ability to evolve into a sentient intelligent species, saved many members of the species from the great extinction and relocated them on a planet in the Delta Quadrant that would give them the best possible chance for survival with safe environmental conditions and protection from outside influence or attack.(Patrick Carroll)

These notions, as common as they may be, are just fanon.
We can regard the depiction of the three-nacelled "dreadnought" in
the Star Trek Technical Manual as canonical because it briefly appeared
in "Star Trek: The Wrath of Khan". But the illegible designation
"dreadnought" is still non-canon. And even if we accept it this one
example is still anything but a proof that all dreadnoughts (if there are any
more besides the Federation class) have three nacelles, or that all
three-nacelled ships are dreadnoughts. The same arguments apply to the
single-nacelled alleged "destroyers".

"The Klingon Bird-of-Prey is an originally Romulan design."

The origin of this common notion is background
information on "Star Trek III" according to which Commander Kruge
was supposed to steal this ship from the Romulans. Hence the name which was
originally meant to be a homage to the Romulan BoP in TOS: "Balance of
Terror". But in the actual movie there is no mention of the Romulans. And
the 22nd century Klingon BoP known since ENT: "The Expanse" is the
ultimate proof that there is no Romulan connection whatsoever.

"Romulan ships were limited to
sublight propulsion until they acquired warp drive during a brief alliance with the
Klingons in 2268, while the Klingons got Romulan BoPs and cloaking."

There are even three mistakes or overinterpretations in this statement:

1. Firstly, there is no evidence that the ship in
"Balance of Terror" or even all Romulan ships until then didn't have warp drive.
The myth came to life because of a line in TOS: "Balance of Terror"
about the Romulans having "simple impulse" although this statement
by Scotty could be easily interpreted differently. But as a consequence, the Star
Trek Chronology explicitly states that Romulan ships during the
Earth-Romulan War had impulse propulsion only, seemingly corroborated by a
depiction of a primitive-looking Romulan ship of that time which is completely
non-canon though. In "Star Trek: Insurrection" it was attempted to
carry the error into canon Trek with a mention of warp drive that "helped to form a bunch of Romulan thugs into an
empire... a century ago". However, a thorough analysis of the topic
of Warp Drive and Romulan History shows
countless lines of reasoning against this notion, and at last ENT:
"Minefield" unmistakably shows old Romulan ships with warp drive.

2.We do not have
any solid evidence that there was a brief alliance between the Romulans and the
Klingons which must have existed since at latest 2268 and likely until the
battle at Klach D'kel Brakt in 2270. The line from TOS: "The Enterprise
Incident" intended to clarify why the Romulans had originally Klingon D7
cruisers was just "They are using Klingon design", not really
implying how the Romulans got their hands on the starships.

3. The Klingon Bird-of-Prey
is a Klingon design and always was. ENT: "Expanse" gives us the
ultimate proof because the Klingon starships resemble the later Klingon BoPs
so closely that it would be a hair-raising theory to claim that the latter
might be acquired from the Romulans more than a century later.

"The Narada is so powerful because Nero outfitted it with Borg technology,
as seen in Countdown."

Until further notice the Star Trek: Countdown comic
series is to be rated as non-canon, and this is not really likely to change. In
an interview
with Trekmovie.com, dated 9 December 2008, Bob Orci said that he personally
considered some novels canon, but that it is not up to him to declare Countdown
canon. In a later Q&A
session, dated May 22, 2009, he explained the inconsistencies between the
movie "Star Trek (2009)" and Countdown with the comic being
non-canon. The same applies to the Star Trek: Nero comics and the whole
story about Nero's imprisonment on Rura Penthe.

"The
Excelsior transwarp experiment was a failure."

Although explicitly stated in the TNGTM, the Excelsior's
transwarp was neither said to be a failure in "Star Trek: The
Undiscovered Country" or in any later episode, nor do we know for sure
that the ship didn't still have transwarp drive when Sulu began his mission in
the Beta Quadrant in 2290. Actually, an equally valid assumption would be that
what used to be "transwarp drive" on the original Excelsior (which
may have nothing to do with Borg transwarp) was called just "warp
drive" in the 24th century.

"The
Sovereign class has Type-12 phasers."

The type of phasers of the Enterprise-E has never been
mentioned on screen, much less that they would be two steps more powerful than
on the Galaxy class. Yet, the idea is corroborated by an entry about the
ship's weapons in Star Trek: The Magazine, October 2001, page 42: "The
phaser arrays installed on the Enterprise are Type XII and have a power output
of 7.2 megawatts." 7.2 megawatts doesn't sound like the most powerful
phasers available, though.

"Riker's command, the Titan, is a Luna-class vessel. It is a canon design."

The Luna-class gained widespread recognition because a
competition was held to decide about the design of the ship for the Star Trek
Titan book series. The winner was Sean Tourangeau. However, all novels
and all of their contents are non-canon, irrespective of their
popularity.

"There are ships named
'City of New Orleans' and 'Royal Sovereign'."

Some fans keep defending these misconceptions with a
passion although there is absolutely no canon ground for the two long names.
The notion that it should be "City
of New Orleans" instead of "New Orleans" is nothing more
than the consequence of an awkward pun in the Star Trek Encyclopedia. "Royal Sovereign" instead of "Sovereign" is
preferred by some fans because it sounds more historically correct to them
(because there was an HMS Royal Sovereign) or just because they have become
accustomed to the FASA design of the same name.

"The Sydney class is an
early runabout, a warp-capable variant of the executive shuttle."

This is an utter misconception considering that the Sydney-class design is many times bigger than a runabout or the said executive
shuttle. The blunder is perpetuated by official publications like the Star
Trek Encyclopedia and the Star Trek Fact Files merely because the
studio model of the Jenolan for TNG: "Relics" was built using parts
of the shuttle.

"NCC" stands for 'Naval Construction Contract.'"

This is one of the most prominent examples of fanon. But
nothing ever mentioned or shown on screen would support this interpretation.
Perhaps we should accept that it's just three letters.

"Enterprise NX-01 is the first ship of its class, so it is the
Enterprise class. The NX registry denotes that it is a prototype ship."

This is wrong on both accounts. Captain Archer
explicitly states that his ship is of the NX class in ENT: "Fortunate
Son", with several more mentions of the class name still to follow. This
already refutes both claims: If NX is the class name, then "NX" in
the registry clearly does not stand for "experimental" in the same
fashion as in the 23rd and 24th century. In addition, we know of two other
ship classes of the 22nd century that are identified by letters instead of
real names, the J class and the Y class. It is possible that, regardless of
the retirement of Enterprise NX-01 as indicated in ENT: "These Are The
Voyages", the naming and numbering scheme may have changed very soon
after the foundation of the Federation. The NX class might have been renamed
"Enterprise class" (although this honor should go to the USS
Enterprise after the refit, as
seen in "Star Trek II"). The new registry system, with
"NX" now meaning "experimental" might have been inspired
by the NX-class numbering scheme. But irrespective of any personal stances on
the NX-01-A riddle, at the time
Enterprise NX-01 was in service there was neither an "Enterprise
class" nor an "experimental ship registry".

More on the Topic

What is Canon?
- definitions, reasons, interpretations and the EAS canon policy

Thanks to all the people at the SCN
who have joined the discussion, particularly to Patrick Carroll for bringing
up the false canon issue and for his suggestions about the female captains, the Voth and
other things. Special thanks to Patrick
Kovacs for pointing out that "Marines" used to exist behind the
scenes and that there is no fixed date for the human-Klingon first contact and
to Cameron Leatham for the quote about the origin of the Borg. The information about the
the name "Rihannsu" comes from Christopher
Mace. The mention of Type-12 phasers was found by Matt.